[Lazarus] TListView: Column Header Captions and Column Sorting

[Michael Van Canneyt]

On Thu, 17 Nov 2022, Aruna Hewapathirane wrote:

> <snip>
>
> Hello again,
>
> I have column headers and sorting works on a button click . Thank you once
> again Michael.
>
> I am trying to figure out how to sort when a user clicks a column header?
>
> Screenshot: https://pasteboard.co/QSf8hNafG0x5.png
>
> And I notice the column headers are sort of greyed out. Is it possible to
> make them bold if we want?
> And the column width am guessing we can set through code?

In the IDE, set a OnColumnClick event handler. Define FLastColumnIndex and
FLastSort as form fields, so your form will look like this:


   TForm1 = Class(TForm)
     ListView1 : TListView;
     procedure ListView1ColumnClick(Sender: TObject; Column: TListColumn);
   private
     FLastColumnIndex : Integer;
     FLastSort : TSortDirection;
   end;

You can also set the event handler in code:

   ListView1.OnColumnClick:=@ListView1ColumnClick;

In the OnColumnClick handler, do the following:

procedure TForm1.ListView1ColumnClick(Sender: TObject; Column: TListColumn);

var
   SD : TSortDirection;

begin
   SD:=sdAscending;
   if Column.Index=FLastColumnIndex then
     if FLastSort=sdAscending then
       SD:=sdDescending;
   ListView1.SortColumn:=Column.Index;
   ListView1.SortDirection:=SD;
   ListView1.Sort;
end;

That should sort ascending if the user clicks on the column for the first
time, and will toggle between ascending/descending if the user clicks 
on the same column.

Michael.